Layer Scanning Imagery Technology on Inner Defects of Spring Flat Steel

When the ultrasonic C-scan image is adopted for full thickness range testing of spring flat steel, focus position must be adjusted with regular interval to keep better testing accuracy. In the research, the height of focusing column is measured and its influences to the C scan imaging are analyzed. And then, the adjusting law of focusing position for C scan imaging is proposed. Besides, the characteristic area of scanning imagery is analysis to decide the defects boundary and which is verified by metallographic test. The results indicate both higher testing accuracy and testing efficiency can be obtained by setting a proper focusing interval according to the height of focusing column, and the boundary of defect imagery proposed in the paper can be used to measure the defect's dimension. Therefore, utrasonic water immersion focusing method can be used to evaluate the dimension and distribution of inner defects in spring flat steel.